On Saturday (September 17), Guns N Roses’ dual 1991 albums Use Your Illusion Iand Use Your Illusion IIturn 25. The anniversary comes just as GNR has wrapped up a hugely successful reunion tour that saw founding members Slash and Duff McKagan back in the fold. It marked the first time that Axl Rose, Slash and Duff performed together since 1993. Absent from the reunion, however, was founding guitarist Izzy Stradlin’, who quit the band in 1991.

This summer’s Guns N Roses reunion could have included the entire original lineup: singer Axl Rose, bassist Duff McKagan, drummer Steven Adler and guitarists Slash and Izzy Stradlin’. Adler joined the band for a few songs at a couple of shows, but Stradlin’, who has filled in with various versions of the band over the years, was a no-show. In a recent interview, Rose said Adler couldn’t do the tour due to a recent back surgery. Stradlin’, however, flaked out, according to the frontman. “I don’t even know what to say,” Rose said. “We make arrangements, and then he goes and does other things. With Izzy, you never know what to expect.” Which seemed like a plausible explanation, as the guitarist has a history of not wanting to tour. But Stradlin’ weighed in on the interview pretty quickly. “Bulls—,” he tweeted. “They didn’t want to split the loot equally. Simple as that.”

After listening to the Use Your Illusion albums and reading the liner notes, one could make a good argument that Stradlin’ is worth his equal share. Prior to those albums, the band split songwriting credits evenly. On the band’s debut, 1987’s classic Appetite for Destruction, Rose, Slash, Stradlin’, McKagan and Alder were all co-writers. This started to change with ’88’s G N’R Lies. Of the older tracks, we learned that the nasty, dirty “Move to the City” was co-written by Izzy with Chris Weber (from pre-GNR band Hollywood Rose). Of the new songs, three were co-written by the entire band. The massive hit “Patience,” however, was a Rose/Stradlin’ co-write.

If you made a playlist of songs from the Illusion albums and included only songs that Stradlin’ wrote, co-wrote or sang on, you’d have a pretty classic album. Let’s go through the songs.

“Right Next Door to Hell” led off I (which boasted more of Stradlin’s influence than II). A co-written track with Rose and Hanoi Rocks associate Timo Kaltio, the song had all the punk rock spit and bile of Appetite and showed none of the Queen-like aspirations that would surface later on the Illusions. It did, however, give a hint of Rose’s paranoia: the lyrics were allegedly inspired by a conflict Rose had with a former neighbor.

From there, we move to track two, one of the band’s Stonesy-est moments, “Dust N’ Bones,” which sees Stradlin’s debut as lead vocalist; he co-wrote the song with Slash and McKagan; Rose simply plays piano and sings backing vocals. It’s a look into what Velvet Revolver may have sounded like if Stradlin’ stuck around and they never approached Scott Weiland. A Stradlin’-led band with Slash, McKagan and drummer Matt Sorum may have lacked some panache without a frontman, but they would surely have been one of the most a–kickin’ bands of the past two decades. At any rate, “Dust N Bones” is one of the greatest, and most underrated, songs in GNR’s cannon.

After the McCartney cover “Live and Let Die,” it’s the album’s first single, the ballad “Don’t Cry,” another Rose-Stradlin’ co-write. These guys clearly had a rapport, particularly with ballads. It’s too bad they don’t write together anymore.

Track five is “Perfect Crime,” an Axl/Slash/Izzy co-write which is quintessentially Stradlin’, combining Stones swagger with Ramones/Clash/Sex Pistols attitude.

Next, a song written solely by Stradlin’, who sings lead: the acoustic kiss-off “You Ain’t the First.” It wouldn’t have sounded out of place on The Stones’ Exile on Main Street, or at least as an Exile outtake.

“Bad Obsession” is a Stradlin’ co-write with GNR associate West Arkeen and is as close to Aerosmith as Guns ever got without covering them. The song featured Hanoi Rocks frontman Michael Monroe adding some very Tyler-esque harmonica, and also saxophone reminiscent of “Same Old Song and Dance.” It was a great, and very rock and roll, and its use of a sax was no easy task. Guns tried to incorporate horns into their touring band after the Illusions were released; by then, Stradlin’ had quit. The horns (and backing singers) made GNR seem like a Vegas act.

Side two of the album featured less of Izzy’s contributions, although a highlight of the Illusions is the Stradlin’ written and sung “Double Talkin’ Jive,” another of the band’s most punk rock moments. And by “punk” we’re talking ’70s and early ’80s punk, not the later hardcore strain. Everything that Stradlin’ did, then and now, has a swing and swagger.

Izzy’s final contribution to Use Your Illusion I is “Bad Apples,” a collab with Axl, Slash and Duff. One of the group’s funkiest songs, it also veers closely to Aerosmith territory, so much so that you could actually hear Steven Tyler singing it. It’s proof of what these four guys were capable of when they worked together.

Use Your Illusion II was less Izzy-centric, but his contributions were pretty massive. Like I, the second song featured Stradlin’ on lead vocals: this time it was on “14 Years,” a co-write with Rose, who sang backing vocals. Had Izzy stayed with the band, and had the band continued, there would have been a good case for giving him 2-3 songs per album (and his solo career provides a couple of potential Guns gems).

“Pretty Tied Up,” another Stradlin’ contribution, was his one dud on the album. And then there was one more Rose/Stradlin’ song: “You Could Be Mine,” a song written in the ’80s that would have fit right in on Appetite for Destruction.

Stradlin’ brought a sense of Stonesy/New York Dolls swagger to Guns N Roses; he seemed to care neither for heavy metal, hardcore punk or the near-prog Queen influences that his bandmates had; he gave the band their swing. With him, they weren’t just a “rock” band: they were rock androll.

Without his contributions: well, they were still great. A version of the Illusions albums minus Izzy’s songwriting contributions would still include their classics “November Rain,” “Civil War” and “Yesterdays,” as well as underrated album tracks “Dead Horse,” “Coma,” “Locomotive (Complicity)” and “Estranged.” And that’s a pretty solid album. But it wouldn’t compare to the alternate-universe single-album Illusion that only has Izzy’s songs. Check this track list: “Right Next Door To Hell,” “Dust N’ Bones,” “Don’t Cry,” “Perfect Crime,” “You Ain’t the First,” “Bad Obsession,” “Double Talkin’ Jive,” “Bad Apples,” “14 Years,” “You Could Be Mine,” and, OK, “Pretty Tied Up.”

It’s sad that the Axl/Slash/Duff/Izzy version of Guns N Roses (whether with Steven Adler or Matt Sorum on drums) said all they had to say in their brief discography. But it’s fair to say that Izzy Stradlin’s contribution was major, and was far greater than his rhythm guitar playing (which itself is an essential element of the band’s early sound).

By most reports, Guns N Roses’ summer concerts were great. They could have been greater: it would have been awesome to see Izzy take the mic for a few songs (a la Keith Richards at Rolling Stones concerts). Guns fans deserve to see performances of “Dust N Bones” and “14 Years.” Maybe next summer.